#include <iostream>
#include <map>
int main_usemap()
{
    using namespace std;
    map<char, int> firstMap;
    firstMap['a'] = 10;
    firstMap['b'] = 20;
    firstMap['c'] = 30;
    map<char, int>::iterator it;
    for (it = firstMap.begin(); it != firstMap.end(); it ++)
    {
        cout << it->first << " => " << it->second << '\n';
    }
    
    return 0;
}
